In today’s Academic Minute, Dr. Paul Keim of Northern Arizona University describes how DNA analysis can be used to trace anthrax outbreaks to their original sources.

Paul Keim is Regents’ Professor and Cowden Chair of Biological Sciences at Northern Arizona University where his teaching and research interests are focused on the genetic analysis of bacteria, fungi, birds, and plants. His work is primarily focused on defining population structure, and in a few cases, Keim has assisted in the forensic investigation of criminal acts. He holds a Ph.D. from the University of Kansas.

Anthrax is a bacterial zoonotic disease found largely in grazing animals but it occasionally infects humans. Of course, anthrax was developed as a biological weapon by Britain, the United States and the Soviet Union. This is scary stuff, but anthrax really is a rare disease today.

Needless to say, it was a big surprise in December 2009 when people started showing up in Scottish emergency rooms with advanced stage anthrax infections. Public health officials quickly noted that the victims were all heroin drug users and that the infections seemed to be linked to this illicit activity. But there were many other questions about this unusual disease outbreak.

Microbial forensics was developed as a rigorous science to investigate disease outbreaks. It was during the anthrax-letter attacks in 2001 that the letters’ source was investigated by sequencing the entire genome of the anthrax bacterium. This allowed the precise identification of the bacterial strain involved in this crime.

Likewise, the anthrax DNA from one of the Scottish victims was sequenced to identify single nucleotide polymorphisms in its genome. We call these SNPs and found some that were unique to the Scottish heroin strain. By comparing the heroin-anthrax SNP profile to our genetic databases, we were able to exclude several well-known anthrax strains: First, this was not the anthrax strain used in the US anthrax-letter attacks. Secondly, it was not a legacy of the British biological weapons program. Next, it was not similar to the weaponized anthrax used by the Soviet Union or the Iraqi governments. And finally, it was not similar to the natural anthrax strains we have observed in Afghanistan. Most of the heroin consumed in Scotland is produced in Afghanistan and this would be a logical point for contamination of the drug.

Rather, we found that it was very similar to anthrax along drug smuggling routes in the Middle East. It appears that the contamination of the heroin was accidental by a smuggler who perhaps wrapped the drug in an animal skin contaminated with anthrax. It was a great relief that this was not a terrorist attack and health officials concentrated on warning drug users of the additional dangers of their habit.

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